Boom and method of manufacturing the same

ABSTRACT

A method of producing a bouyant boom made of a flexible material impermeable to water and air. An elongated sheet of the flexible material is initially disposed in an unfolded position. The sheet has first and second portions disposed adjacent the opposite edges and extending longitudinally thereof, which first and second portions are separated by an intermediate portion. Expander devices are attached to the first and intermediate portions of the sheet at spaced intervals therealong, and pieces of flexible material are also disposed on said sheet at spaced intervals between the expander devices so as to extend transversely across the first and intermediate portions. The pieces are sealed along one edge thereof to said first and second portions in a direction transversely thereof. The first portion of the sheet is then folded to overlap the intermediate portion, which also causes a folding over of the pieces. The first portion is then sealed adjacent the free edge thereof to said intermediate portion to form a hoselike expandable portion, and the free edges of the pieces are also sealed together to form liquid-tight partitions which extend across the hoselike portion and divides same into chambers. The second edge portion of the sheet is permitted to freely extend from the hoselike portion to form a depending curtain.

United States Patent n91 jberg BOOM AND METHOD OF MANUFACTURING THE SAMEPer ()lot Dberg, Sollentuna, Sweden [73] Assignee: Sanera ProjectingAktiebolag,

Bromma, Sweden 22 Filed: Nov. 28, 1973 21 Appl.No.:4l9,677

Related US. Application Data [62] Division of Ser. No. 129,932, March31, 1971, Pat.

[75] Inventor:

[58] Field of Search...6l/l F.l R:2l()/242.D|G.2l; 52/2; 138/118, 119;156/218, 213,145,147, 65, 203, 204, 200, 20l, 227

[56] References Cited UNITED STATES PATENTS 2,515,806 7/1950 Spanel156/65 3.364.632 1/1968 Isaac 52/2 3,579,994 5/1971 Preus 61/1 F3,592,007 7/1971 Renncr 61/] F FORElGN PATENTS OR APPLICATIONS 1,243,1768/1971 United Kingdom 61/1 F [4 1 Aug. 26, 1975 Primary ExaminerCharlesE. Van Horn Assistant ExaminerDavid A. Simmons Attorney, Agent, orFirm-Woodhams, Blanchard and Flynn [57] ABSTRACT A method of producing abouyant boom made of a flexible material impermeable to water and air.An elongated sheet of the flexible material is initially disposed in anunfolded position. The sheet has first and second portions disposedadjacent the opposite edges and extending longitudinally thereof, whichfirst and second portions are separated by an intermediate portion.Expander devices are attached to the first and intermediate portions ofthe sheet at spaced intervals therealong, and pieces of flexiblematerial are also disposed on said sheet at spaced intervals between theexpander devices so as to extend transversely across the first andintermediate portions. The pieces are sealed along one edge thereof tosaid first and second portions in a direction transversely thereof. Thefirst portion of the sheet is then folded to overlap the intermediateportion, which also causes a folding over of the pieces. The firstportion is then sealed adjacent the free edge thereof to saidintermediate portion to form a hoselike expandable portion, and the freeedges of the pieces are also sealed together to form liquid-tightpartitions which extend across the hoselike portion and divides sameinto chambers. The second edge portion of the sheet is permitted tofreely extend from the hoselike portion to form a depending curtain.

7 Claims, 15 Drawing Figures PATENTEBAUGZSIWS 3, 901 ,753

sum 1 or 7 PATENTEUAUBZBIQYS 3 901 7513 saw 5 or Y l BOOM AND METHOD OFMANUFACTURING THE SAME This is a division of application Ser. No. D9932,filed M.|r 'il. HYl. now US. Pat. Nov 3,798,911.

The present ln ention refers to a boom and a method of manufacturing thesame.

Harmful impurities floating on the surface of water must be screened-offand neutralized as quickly as possible. This is particularly true foroil slicks resulting from the intentional or unintentional release ofoil from oil carrying ships. The most expedient device for screening-offoil slicks is the boom. A modern boom construction consists of one ormore buoyant bodies, which hold the boom afloat on the surface of thewater. Depending from the buoyant bodies down to a specific, suitabledepth below the surface of the water is a curtain which is firmlyconnected to the buoyant bodies and which is provided at its bottom withweights to ensure that the curtain constantly occupies a substantiallyvertical position in the water.

The area of water surface impurified by the release of oil is often verywide for example such an area may be several kilometers in length andwidth. In order to impede and contain an oil belt of this magnitude, oneor more chains of booms are required, the boom chains of necessityhaving great length and consisting of a larger number of booms of some25 meters in length. This means that it must be possible to lay out andconnect up the booms in a quick and simple manner. The individual boomsshould be so constructed that when it is desired to lay the booms outthey can be released from their stowed condition rapidly and easily. Itshould also be possible to lay out the booms from a boat or ahelicopter. Moreover, it should be possible, either while placing thebooms in position or immedi ately afterwards, to connect the boomstogether to form a continuous, sufficiently long chain of booms in asimple and positive manner. The boom chain can then be towed andmanouvered to enclose the oil belt in a closed ring of booms, whereafterthe oil can be rendered harmless or moved to a suitable site fordestruction.

The disadvantage with booms hitherto known to the art is that they areeither very bulky, making it difficult to store and stow the same, oralso require special working operations when laying them out on the surface of the water. This latter disadvantage is related to the manner inwhich the booms are floated in the water. In order to hold the boomsbuoyant, different types of floats are used for example balls orinflated cushions of a plastics material for example, attached to theboom. There may be attached to the boom a hose which is inflated with aspecial inflating medium when the boom is layed out, and emptied of theinflating me dium when the boom, after having been in use, is rolled upor folded. The arrangement of balls or cushions requires a large storagespace, while the hose arrange ment requires special working operation tobe effected when laying out the booms.

The object of the present invention is to circumvent these disadvantagesand the invention relates to the type of boom which includes buoyantbodies which are gncn their shape by the expansion of collapsablecavities. and is mainly charactcri/ed in that each cavity in cludes oneor more expander means It is of particular importance that the oom iscon structed o that In practice it can automatically and rapidly expandin direct connection with the laying out of the boom, and that theexpanded boom can be coupled reliably and simply to a similar boom. Inview of the increasing urgency for the care and protection ofenvironment, the need of booms will probably be great and it is of theutmost importance that large series of booms can be manufactured in anefficient manner. The booms at present available do not fulfill all ofthe requirements placed thereon and it is a further object of theinvention to provide a boom manufacturing method which fulfills allnecessary requirements.

An embodiment of a boom according to the invention will now be describedwith reference to the accompanying drawings.

FIG. 1 illustrates a train of booms being towed by two boats whileenclosing a small oil slick.

FIG. 2 is a perspective view of a portion of a boom according to theinvention.

FIG. 3 is a horizontal sectional view of a portion of a boom andillustrates how two booms constructed according to the invention arecoupled together.

FIG. 4 is a horizontal view ofa pre-worked length of material for use inconstructing the boom of the invention.

FIG. 5 illustrates in section and in principle how the length ofmaterial illustrated in FIG. 4 is formed into a boom.

FIG. 6 illustrates the different working operations performed whenforming the boom of the invention.

FIG. 7 illustrates in perspective a coupling effected between two boomsconstructed in accordance with the invention.

FIG. 8 illustrates in perspective and partially in section a portion ofan expanded boom constructed in accordance with a further embodiment ofthe invention and placed on the surface of the water the FIGURE alsoshowing the normal position of the boom, on the surface of the waterwhen not subjected to lateral forces as a result of wind or wavepressure.

FIG. 9 illustrates the portion of the boom shown in FIG. 8 when the boomis subjected to lateral forces resulting from wind or wave pressure.

FIG. I0 illustrates in perspective coiling of the boom shown in FIG. 8and 9.

FIG. II illustrates in perspective an expander means according to theinvention, intended to be attached in the wall of a buoyant body of theboom of FIG. 8, the expander means being illustrated in its extendedcondition.

FIG. 12 illustrates in perspective an alternative em bodiment ofa framemember of the expander means of FIG. 11.

FIG. 13 is a section taken throught the line ll in FIG. II of theexpander means in a compressed condi tion i.c., non-extended condition.

FIGS. I4 and I5 illustrate in section different positions for a latchingmember of one embodiment of a latching means according to the invention.

Illustrated in FIG. I are four booms [-4 coupled to' gether at theirends at positions 57 and being towed by their free ends 8 and 9 by twoboats IO and II. The reference numeral I2 indicates an oil slick whichis to be enclosed and rendered harmless.

FIG. 2 illustrates a portion of a boom ha\ing an up per. substantiallycylindrical buoyant body in the form of a hose I3 and a dependingcurtain I4 fixedly at tachcd to the hose l3. The curtain I4 is providedat the bottom edge thereof with weights to ensure that the curtainconstantly adopts a substantially vertical attitude in the water.Arranged in appropriate spaced apart relationship within the hose 13 areexpander means 16, which consist of two resiliently, flexible platelikestirrup members 160 and [6b which have their opposite ends connected bya tension spring 4] which actuates said stirrup members so that saidopposite ends are pulled toward one another causing the members 16a and16b to assume a somewhat semicylindrical shape for causing expansion ofthe hose. Valve means 17 are arranged substantially on the upper side ofthe hose 13 to permit air to be introduced to inflate the hose and torelease the air when the boom is rolled up or folded after use. Thevalve means l7 are of the type which permit air to pass therethrough butwhich prevent water from penetrating the interior of the hose.

The reference numerals l8 and 19 in FIG. 2 indicate depressions in thehose [3. The depressions l8 and 19 are correlated with the method formanufacturing the boom and with the fact that the hose according to theinvention is divided into sections, each of which has a length L andforms a divided portion of the hose 13 as shown in FIG. 2. The divisionof a boom hose into connected sections which, with respect to the innervolume of the hose, are completely separated from each other. isnecessary from the point of view of the necessary buoyancy of the boom.For example, if the boom hose was constructed of one continuous sectionand became damaged or punctured the hose is liable to become full ofwater and sink. Damage to one or more sections of a boom constructed inaccordance with the present invention will have no great effect on theeflicieney of the boom, and a relatively large number of sections may bedamaged without rendering the boom completely unservicable.

FIG. 3 further illustrates the division of the boom hose into sectionsL. The partitions arranged between the sections are in the form ofpockets 20 which are connected to the wall of the hose [3 in an airtightmanner hereinafter described. The reference numeral 21 in FIG. 3indicates generally a first boom which is coupled to a second boom 22through a coupling joint 23. The joint 23 is created by passing the hoseof boom 21 over the end pocket 24 through a distance S and is terminatedwith a rope 25 attached to the mouth of the hose and passing around thesame, while a snaphook means 26 is fastened to the left and (FIG. 3) ofthe boom 22 in a manner whereby the extended portion of the hose of boom21 extends slightly over the boom 22. This method of coupling two boomstogether is illustrated more clearly in FIG. 7.

The aforementioned expander means for radially extending the boom hoseare indicated by the reference numeral l6 in FIG. 3. Two such expandermeans have been shown for each section. A suitable position for the airvalves I7 in each section has been shown with dotted circles in FIG. 3.The left end section of the boom 22, i.e.. the end provided with thesnap-hook means 26, has an end pocket 27 which is suitably directed inthe opposite direction to the remaining pockets 20. On the other hand.the right end pocket 28 of the boom 22 is directed in the same directionas the remaining pockets 20 and. similarly to the boom 2I. this end ofthe boom 22 is provided with an extension S which is terminated with arope ferrule 29 for connecting the boom to a third boom in the mannerpreviously described.

The method for manufacturing the boom of the invention is illustrated inFIGS. 4-6. FIG. 4 illustrates a sheet 30 of the material from which thehose and curtain of the boom are made. The sheet 30 consists of awater-tight and air-tight material, for example a plastics or rubbercloth, plastics or rubber impregnated fabric or the like. The totallength Ll is equal to the length of the boom, for example 25 meters, andthe width B of the sheet 30 corresponds to the total distance requiredto form both the hose l3 and the curtain 14 (FIG. 5). A rectangularportion having a width 51 has been clipped out of the left side of theportion of the sheet 30 forming the curtain l4 and a recess 31 has beenmade, for reasons hereinafter desclosed.

The first working step to be made on the pre-formed sheet 30 is toattach the valves 17, or suitable valve holder means, in the sheet. Thevalves or valve holders can be attached by sewing, adhesion or heatsealing, as can all subsequent component attaching operations. It isimportant, however, that the attachment joints are water-tight andair-tight. Attachment pockets 32 in tended as attachment means for theexpander means 16, are then secured to the sheet 30 in a similar way,together with cloth pieces 33 intended to form sealing pockets for thedifferent sections for the boom. The attachment flaps 32 and the clothpieces 33 are only attached along their left edge surfaces. i.e. alongseams 34 and 35 and at positions on the sheet 30 which correspond to thefinal positions for the expander means 16 and the pockets 20. The snaphook means 26 are attached to the outside of the left end of the sheetof material 30.

Subsequent to attaching the components 32, 33 aand 26, that portion ofthe upper part of the sheet 30 which is to form the hose I3 is foldedaround its centre line 36 so that the folded portions lie flat againsteach other. The boom hose is then finally assembled by joining togetherthe end edge portions 37 and simultaneously forming a small part of alongitudinal seam or joint 38. The expander means 16 are then placed inposition and fixed by means of the attachment flaps 32 while thelongitudinal seam or joint 38 is successively formed from left to rightas seen in FIG. 6. In FIG. 6 a first completed section of the hose isindicated by the reference numeral 39 to the left of the Figure, whilethe section being assembled is indicated by the reference numeral 40.Construction of the hose continues in stages, the attachment flaps 32and the cloth pieces being successively placed in position prior to thelongitudinal seam 38 being formed. FIG. 6 illustrates by way of examplehow an expander means 16 is placed between two attachment flaps 32', ofwhich only one is shown in the Figure. The previously free edge surfacesof the attachment flaps 32' are then joined to the sheet of material 30so as to secure the expander means 16' in the hose in a manner wherebythe expander means is permitted some degree of movement therein. Theexpander means 16' may include a tension spring 41, FIGS. 2 and 7. Thespring 41 is disengaged from the expander means l6 when placing theexpander means in posi tion, and is then reconnected with the expandermeans to extend the hose as indicated to the left of FIG. 6.

Each pocket 20 (FIG. 3) is formed by a cloth piece 33 as illustrated inFIG. 6. A double folded edge 42 obtained with the cloth-piece 33subsequent to folding the sheet of material 30 is then joined along ajoin line 43, whereafter folding of the length of material 30 iscontinued together with the forming of the longitudinal seam joint 38.Two previously free edges 44 and 45 of the clothpiece 33 then becomeclamped between parts of the folded length of material 30 and sealinglyjoined thereto.

Subsequent to the complete hose having been stepwise but continuouslyjoined together in the aforementioned manner the rope ferrule 25 is thenplaced on the right side of the hose, as seen in the drawing, and theweights attached to the bottom edge of the boom curtain 14.

FIG. 7 illustrates how two booms are joined together and shows the ropeferrule at the right end of a boom 1 as seen in the drawing, and twospring-hook means 26 at the left end of a second boom 1'. It isimportant that the curtains l4 and 14" of the two booms at the positionwhere they are joined is impermeable to oil. Consequently, the curtainsl4" and M are made to overlap each other through a distance 82, thisdistance being obtained through the aforementioned construction of thecurtain portion according to FIG. 4 and by the fact that the right endof the boom 1' is passed over the left end of the boom 1' to such anextent to the rope ferrule 25 passes into the recess 31 on the curtain14" of the left boom I".

The spring-hook means 26, 26' (FIGS. 3, 4, 7) can be in the form of aself-locking quick coupling of known type which enables two booms to beconnected and disconnected in a simple and easy manner.

The manufacturing method according to the invention enables the booms tobe produced in a simple, expedicnt and inexpensive manner and a boomconstructed in accordance with the method of the invention can be layedout rapidly, automatically expanded and coupled to similar booms in asimple and effective manner, to form long boom chains which build aneffective enclosure against oil or other impurities. Moreover, a boomconstructed in accordance with the in vention can be simply and quicklyrolled-up or folded into a small volume for packaging or storage in aposition of readiness.

For the purpose of towing chain of booms constructed in accordance withthe invention, the towing means can be simply attached to the ropeferrule 25 and the hooking means 26. A chain of booms according to theinvention can be connected up to form a complete enclosing ring byattaching the rope ferrule 25 at one free end of the boom chain to thehook means 26 at the other free end of the chain. By suitably modifyingthe sheet of material 30 when producing the same, it is possible toexclude the recesses 18 and I9 illustrated in FIG. 2.

Booms of large dimensions intended to be used at sea or for morecomprehensive decontamination work in open water can, in rough weatherbe subjected to high wind and wave pressures, which cause the buoyantbodies to be unfavorably deformed. Under such conditions, the bodies areflattened by the wind and waves and pressed down against the surface ofthe water, thereby reducing the intended screening effect of the boomand also its buoyancy. Deformation and flattem ing of the hose may occurwhile the booms are being towed to ring an oil slick. allowing some ofthe enclosed oil to be blown or thrown by the wind and wave movementover the buoyant bodies. The escaped oil must then be collected andscreenedoff in a new boom enclosure.

The tendency of the buoyant bodies used with the above described type ofbooms to yield to wind and wave pressure is primarily due to theconstruction of the expander means. When the walls of the boom aresubjected to natural forces of sufficiently high magnitude the expandermeans (the spring 44) yields to said forces and the buoyant body iscompressed. FIGS. 8-]! illustrate an embodiment which enables thebuoyant bodies to extend automatically to maximum volume and to belocked in this condition by a special device which can only be releasedby manual activation when the booms are being rolled-up or folded afteruse. In FIG. 8 the reference numeral 46 indicates generally a boomconsisting of a number of sections joined end to end, two sections 47and 48 being shown. As previously described, each section 47, 48includes a buoyant body 49 and a curtain 50 having attached at thebottom thereof weights 51.

Arranged within each section 47, 48 in the manner aforedeseribed areexpander means 52 according to the invention. FIG. 8 illustrates how theboom behaves in quiet weather, while FIG. 9 illustrates how in roughweather the boom is liable to tilt and lie on one side thereof, while atthe same time another side of the boom is pushed inwards by wind andwave pressure. The thus occuring forces attempt to compress the hose,and the expander means 52 must be so arranged that compression of thehose is prevented. At the same time, however, it must be possible toeliminate the effect which counteracts the compression of the boom in asimple manner, so that the boom can be easily rolled up, as illustratedin FIG. 10.

FIGS. 11-15 illustrate an embodiment of the expander means 52 accordingto the invention, having a frame generally indicated at 53, consistingof two frame pieces 54 and 55, a tension spring 56 and two springattachments 57, 58. The frame pieces 54, and the spring attachments 57,58 are suitably manufactured of a plastics material which enables themto be assembled together by heat welding. The spring attachments 57, 58are provided with flanges 59, 60 (of which only the flange 59 isillustrated in FIG. 11) and end portions 61, 62 on the frame pieces 54,55 engage the flanges in a fixed joint produced by heat welding forexample.

The frame pieces 54, 55 may comprise plastic plates of suitable widthand thickness. To provide for the necessary pivot points, the framepieces are provided at the end portions 6|, 62 thereof and substantiallyin the centre thereof with thickness reducing recesses 63, which atthese positions reduce the resistance of the frame pieces to bending sothat hinge-like folding portions have a certain degree of resiliency areobtained.

The frame pieces 54, 55 are subjected to lateral bending forces bothwhen compressed and when expanded and must therefore be sufficientlyrigid. This rigidity can be provided for by appropriate dimensioning ofthe frame pieces 54, 55. It is, however, also possible to use asstarting material a relatively thin bar 64, (FIG. 12) which onsubstantially straight portions of the frame pieces 54, 55 is providedwith beads 65 to strengthen the Same against bending moments. No special recesses 63, (FIG. ll) need then be provided, but that the thin bar64 functions at the portion 66 and adjacent the end portions 6|, 62 as ahinge means.

The expander means 52 according to the invention is provided withlatching means, generally indicated at 67 in FIG. 11, which prevents theexpander means, and there by also the boom 46, from being pressedtogether as a result of lateral wind and wave pressure forces. In theembodiment illustrated in FIGS. ll, l3, l4 and the latching means 67includes a stiff wire 68 arranged within the tension Spring 66 andprovided at the bottom end with a bent portion 69 and at the other endwith an eye piece 70, FIG. 13. The bent portion 69 is grouted in aplastic end piece 71, FIG. 13, the diameter of which is so adjusted withrespect to an opening 72 in the spring seating 58 that a light press fitis obtained. To assist in retaining the end piece 71 in position in thespring seating 58, the end piece 71 is provided with a rivet-like head73 and a circumferential gripping edge 74, which effectively locks theend piecesecurely inth'e spring seating 58.

Arranged in the eye member 70 is a latching piece 75, which in theembodiment of FIGS. ll, l3, l4 and 15 consist of a wire folded to forman elongated, narrow eye member having a link portion 76 which passesthrough the guide eye 70, and an outwardly projecting portion 77 whichis slightly shorter than the elongated, narrow eye portion of thelatching member 75. The fit so that an easily movable link connection isobtained between the latching piece 75 and the wire 68.

When the frame is compressed, so that the frame pieces 54, 55 aresubstantially parallel, the tension spring 56 is fully extended. Thelatching means 67 then occupies the position in the tension spring56illustrated in FIG. 13. The latching member 75 is dimensioned to enableit to slide easily within the tension spring 56 and through an opening78 arranged coaxially in the spring attachment 57. When the boom is laidout on the surface of the water, the expander means are released fromthe lateral forces to which they are sub- 2 jected in the rolledcondition of the boom and the tension spring 56, via the springattachment 57, 58, draws the end portion 61, 62 towards each other sothat the frame pieces 54, 55 take the position illustrated in FIG.

11. The latent tension forces in the frame pieces 54, 55

also act in the same direction, these forces voccuring when bendingalong the recesses 63.

Simultaneously as the expander means 52 takes a,

between the eye 70 and the link portion 76 is very light,

eye-shaped portion of the latching member, the latching member 75automatically falls down into the latching position illustrated in FIG.14. FIG. 14 also illustrates with dashed lines the actual releaseposition of the latching member 75. The force of the tension spring 56and the length of the wire 68 are so adjusted that subsequent to thespring being fully expanded, a dis tance S is obtained, FIG. 14, whichpermits the latching member 75 to fall freely on either side.

If the boom 46 is subjected to lateral forces of such magnitude that thetension forces exerted by the spring 56 are overcome, the frame pieces54, 55 are pressed together. This causes the wire 68 to be drawn downthrough the opening'lS so that when the distance S be comes zero and thelatching member 78 abuts the spring seating 57 in,a,latching position asillustrated in FIG. 15.

Latching of the expander means 52 is thus effected fully automaticallyand the latching member 67 can only be released by manual activation.This is done when the boomis rolled up after use, all latching membersbeing successively adjusted as the boom is rolled up so that theoutwardly projecting portion 77 ,extends into the tension spring 56whereupon the latching membentakes the position illustrated in FIG. 13.

When the boom is expanded or compressed it is important thatsatisfactory communication with the atmo- .-sphere is provided. Aspreviously mentioned, the ex- 'is, made by. heat sealing or adhesion ina manner whereby a durable and tight joint is obtained. The frame pieces54, 55, as an alternative to the previously described method ofattachment, can be connected to the walls of the boom in a correspondingmanner. Since the remainder of the boom is fully closed, the hole 78will form a communication opening between the outer air and theinteriorof the boom. The hole 78 can be made sufficiently large toprovide satisfactory communication and, at the same time, may besufficiently small to prevent appreciable penetration of water into thebuoyant bodies. To provide for very rapid expansion, it may be necessaryin practice to provide separate air inlet valves in the boom.

The joint between the lower spring attachment 58 and the lower vi/allofthe boom may substantially be the same 'as that described withreference to the spring attachment 57.

A boom can be subjected to high stresses and strains from wind, saltwater, cold etc. It is therefore obvious that the choice of materialsmust be made carefully. The plastic portions should not be brittle atlow temperatures and all metal components, for example the tensionspring 56, the wire 68 and the latching member 75 must be 'made of acorrosion resistant material.

It can be mentioned in addition to the aforegoing with respect to thefunction of a boom according to the invention that with comprehensivedecontamination operations a larger or small number of booms must beconnected to form a'trairi of booms which is towed at the two outer endsover the area to be decontaminated, whereby it is often necessary tojoin the two ends of the boom chain to fully enclose the contaminatingoil or the like. In such cases it is suitable to fold the booms togetherin zig zag form in bundles, in a manner whereby the two ends of the boomare accessible and capable of being connected to adjacent booms beforethe booms are laid out on the water, so that the operation ofrlaying outthe booms can be carried out continuously.

As previously mentioned, it is important in rough weather that thebuoyant bodies of the boom are not compressed. This is effectivelyprevented by means of the latching means according to the invention.

The quadratic or rhomboidal shape of the boom 46 in the expandedposition is advantageous with respect to the expansion of the boom butalso affords a significant extra effect with regard to the ability ofthe boom to held oil or other impurities of the water surface enclosed.This extra effect is illustrated in FIG. 9, which shows how a boom hasbeen capsized by wind and wave pressure and/or while being towed andlies on a substantially flat side 80. An adjacent side 8| is subjectedin this position to the pressure from wind and waves and becomessomewhat arched as illustrated in the Figure and, together with thecurtain 50 forms a screening wall which prevents the impurities and thewater driven against the wall 81 from breaking over the same.

It will be understood that the frame pieces 54, 55, of the expandermeans 57 and the latching means 67 are not restricted to the describedembodiment but can have any appropriate construction. Moreover, theinvention is not restricted to the described construction of thecavities formed in the boom but that the cavities can be formed in anymanner appropriate to the buoyancy of the boom.

The aforedescribed boom can be laid out rapidly, is automaticallyexpanded and can be connected simply and effectively to form long boomchains which positively enclose oil or other impurities floating on thesurface of the water. The manufacturing method of the present inventionprovides a simple, expedient and inexpensive method of manufacturing theboom according to the invention. The described expander meanseffectively prevents the boom from being compressed as a result of windand wave pressure and, at the same time, enables the boom to be rolledup or folded together simply and rapidly to a small volume for packagingor storing in a position of readiness. In accordance with the inventionthere may be such embodiments at which the expanding means are to beactuated manually in order to obtain the expansion of the buoyant bodiesbefore putting the boom into the water and in such a case locked in anexpanding position.

What is claimed is:

l. A method of producing a boom or similiar bouyant body made of amaterial impermeable to water and air, for example rubber, plastic orimpregnated fabric. and having a hoselike expandable upper portion and acurtainlike lower portion which depends into the water from the upperportion, comprising the steps of:

providing an elongated sheet of a flexible material which is impermeableto water and air, said sheet including first and second sheet portionsdisposed adjacent the opposite longitudinally extending edges of saidsheet and extending longitudinally throughout said sheet. said sheetalso including an intermediate sheet portion extending longitudinally ofsaid sheet and disposed between said first and second sheet portions;

initially positioning said sheet so that at least the first andintermediate sheet portions are in a substantially unfolded condition;

mounting a plurality of expander devices on the intermediate sheetportion at longitudinally spaced intervals;

providing a plurality of flexible sheetlike pieces constructed from amaterial which is impermeable to water;

positioning said pieces at spaced intervals along said sheet so that theindividual pieces extend transversely across said first and intermediatesheet portions;

sealing a transversely extending edge of said pieces to said first andintermediate sheet portions; folding said first sheet portion, so thatit overlaps said intermediate sheet portion, thereby enclosing saidexpander devices and said pieces, the folding of said first sheetportion so as to overlap said intermediate sheet portion also causing afolding of the pieces; sealing the free edges of the pieces to oneanother to form a liquid-tight partition which extends completely acrossthe hoselike portion defined by the overlapping first and intermediatesheet portions;

sealing the first sheet portion adjacent the longitudinally extendingedge thereof to said intermediate sheet portion in a liquid-tight mannerso as to form a hoselike bouyant body containing therein said expanderdevices and said liquid-tight partitions; and

permitting the second sheet portion to project freely outwardly from thehoselike bouyant body to form a downwardly depending curtain when theboom is disposed in a body of water.

2. A method according to claim 1, including the steps of providing oneof said first and intermediate sheet portions with holes formed thereinclose to the borderline thereof, and securing air valves within saidholes.

3. A method according to claim 1, including the step of maintaining saidexpander devices in at least a partially expanded state when the firstsheet portion is longitudinally sealed to said intermediate sheetportion.

4. A method according to claim 1, wherein the pieces are initiallypositioned closely adjacent the expander devices.

5. A method according to claim 1, including the step of securing theexpander devices to the first sheet portion after same has been foldedover so as to overlap the intermediate sheet portion but prior to thefirst sheet portion being longitudinally sealed to the intermediatesheet portion.

6. A method according to claim 1, including the steps of folding overthe first sheet portion so as to overlap the intermediate sheet portionand positioning same so that the free longitudinally extending edges ofsaid pieces also overlap one another and are positioned in the vicinityof the free longitudinally extending edge of said first sheet portion,and then sealing the longitudinally extending free edges of the piecesand sumultaneously therewith sealing the free edge of the longitudinallyextending free edge of said first sheet portion to said intermediatesheet portion so that the longitudinally extending free edges of saidpieces are also sealed to the free edge of said first sheet portion.

7. A method according to claim 1, including the steps of providing aplurality of pairs of sheetlike members formed from a flexible waterimpermeable material, one pair of said sheetlike members beingassociated with each expander device. positioning one pair of saidsheetlike members on said sheet so that one sheetlike member ispositioned on said first sheet portion and the other sheetlike member isspaced transversely from said one sheetlike member and is positioned onsaid intermediate sheet portion, sealing each of said sheetlike membersto its respective sheet portion along one transversely extending edgethereof, then positioning said expander device on said sheet so that itis partially engaged with said other sheetlike member, and then aftersaid first sheet portion has been folded so as to overlap saidintermediate sheet portion, then sealing the other transverselyextending edges of said sheetlike members to the respective sheetportions.

1. A METHOD OF PRODUCING A BOOM OR SIMILAR BOUYANT BODY MADE OF AMATERIAL IMPERMEABLE TO WATER AND AIR, FOR EXAMPLE RUBBER, PLASTIC ORIMPREGENATED FABRIC, AND HAVING A HOSELIKE EXPANDABLE UPPER PORTION ANDA CURTAINLIKE LOWER PORTION WHICH DEPENDS INTO THE WATER FROM THE UPPERPORTION, COMPRISING THE STEPS OF: PROVIDING AN ELOGANATED SHEET OF AFLEXIBLE MATERIAL WHICH IS IMPERMEABLE TO WATER AND AIR, SAID SHEETINCLUDING FIRST AND SECOND SHEET PORTIONS DISPOSED ADJACENT THE OPPOSITELONGITUDINALLY EXTENDING EDGES OF SAID SHEET AND EXTENDINGLONGITUDINALLY THROUGHOUT SAID SHEET, SAID SHEET ALSO INCLUDING ANINTERMEDIATE SHEET PORTION EXTENDING LONGITUDINALLY OF SAID SHEET ANDDISPOSED BETWEEN SAID FIRST AND SECOND SHEET PORTIONS, INTIALLYPOSITIONING SAID SHEET SO THAT AT LEAST THE FIRST AND INTERMEDIATE SHEETPORTIONS ARE IN A SUBSTANTIALLY UNFOLDED CONDITION, MOUNTING A PLURALITYOF EXPANDER DEVICES ON THE INTERMEDIAATE SHEET PORTIONS OFLONGITUDINALLY SPACED INTERVALS, PROVIDING A PLURALITY OF FLEXIBLESHEETLIKE PIECES CONSTRUCTED FROM A MATERIAL WHICH IS IMPERMEABLE TOWATER, POSITIONING SAID PIECES AT SPACED INTERVALS ALONG SAID SHEET SOTHAT THE INDIVIDUAL PIECES EXTEND TRANSVERSELY ACROSS SAID FIRST ANDINTERMEDIATE SHEET PORTIONS, SEALING A TRANVERSELY EXTENDING EDGE OFSAID PIECES TO SAID FIRST AND INTERMEDIATE SHEET PORTIONS, FOLDING SAIDFIRST SHEET PORTION, SO THAT IT OVERLAPS SAID INTER MEDIATE SHEETPORTION, THEREBY ENCLOSING SAID EXPANDERDEVICE AND SAID THE FOLDING OFSAID FIRST SHEET PORTION SO AS TO OVERLAP SAID INTERMEDIATE SHEETPORTION ALSO CAUSING A FOLDING OF THE PIECES, SEALING THE FREE EDGES OFTHE PIECES TO ONE ANOTHER TO FORM A LIQUID-TIGHT PARTITION WHICH EXTENDSCOMPLETLY ACROSS THE HOSELIKE PORTION DEFINED BY THE OVERLAPPING FIRSTAND INTERMEDIATE SHEET PORTIONS, SEALING THE FIRST SHEET PORTIONADJACENT THE LONGITUDINALLY EXTENDING EDGE THEREOF TO SAID INTERMEDIATESHEET PORTION IN A LIQUID-TIGHT MANNER SO AS TO FORM A HOSELIKE BOUYANTBODY CONTAINING THERIN SAID EXPANDER DEVICES SAID LIQUID-TIGHTPARTITIONS, AND PERMITTING THE SECOND SHEET PORTION TO PROJECT FREELYOUTWARDLY FROM THE HOSELIKE BOUYANT BODY TO FORM A DOWNWARDLY DEPENDINGCURTAIN WHEN THE BOOM IS DISPOSED IN A BODY OF WATER.
 2. A methodaccording to claim 1, including the steps of providing one of said firstand intermediate sheet portions with holes formed therein close to theborderline thereof, and securing air valves within said holes.
 3. Amethod according to claim 1, including the step of maintaining saidexpander devices in at least a partially expanded state when the firstsheet portion is longitudinally sealed to said intermediate sheetportion.
 4. A method according to claim 1, wherein the pieces areinitially positioned closely adjacent the expander devices.
 5. A methodaccording to claim 1, including the step of securing the expanderdevices to the first sheet portion after same has been folded over so asto overlap the intermediate sheet portion but prior to the first sheetportion being longitudinally sealed to the intermediate sheet portion.6. A method according to claim 1, including the steps of folding overthe first sheet portion so as to overlap the intermediate sheet portionand positioning same so that the free longitudinally extending edges ofsaid pieces also overlap one another and are positioned in the vicinityof the free longitudinally extending edge of said first sheet portion,and then sealing the longitudinally extending free edges of the piecesand sumultaneously therewith sealing the free edge of the longitudinallyextending free edge of said first sheet portion to said intermediatesheet portion so that the longitudinally extending free edges of saidpieces are also sealed to the free edge of said first sheet portion. 7.A method according to claim 1, including the steps of providing aplurality of pairs of sheetlike members formed from a flexible waterimpermeable material, one pair of said sheetlike members beingassociated with each expander device, positioning one pair of saidsheetlike members on said sheet so that one sheetlike member ispositioned on said first sheet portion and the other sheetlike member isspaced transversely from said one sheetlike member and is positioned onsaid intermediate sheet portion, sealing each of said sheetlike membersto its respective sheet portion along one transversely extending edgethereof, then positioning said expander device on said sheet so that itis partially engaged with said other sheetlike member, and then aftersaid first sheet portion has been folded so as to overlap saidintermediate sheet portion, then sealing the other transverselyextending edges of said sheetlike members to the respective sheetportions.